1. Field of the Invention
The present general inventive concept relates to a test unit to test a board having an area array package mounted thereon, and more particularly, to a test unit placed in an area array package and a board to test a connection state between the area array package and the board.
2. Description of the Related Art
An area array package is used for connecting electronic components to a board by soldering, or the like, and includes a ball grid array (BGA) package, a chip size package (CSP), a wafer level package (WLP), a flip chip package, or the like.
Hereinafter, the BGA package will be described as the area array package.
A conventional structure for mounting the BGA package to the board is disclosed in Korean Patent Application No. 1995-10124. The BGA package comprises a semiconductor chip, a plurality of solder balls positioned on the bottom of the semiconductor chip to be adhered to the board, and a plurality of supporters protruding outward and downward from the plurality of solder balls. Further, the board comprises a plurality of connection parts to be connected with the plurality of solder balls on the BGA package, and a plurality of supporting grooves formed outside the plurality of the connection parts to accommodate the supporters therein.
In the conventional structure for mounting the BGA package to the board, the plurality of supporters are inserted in the plurality of supporting grooves on the board, and at the same time the plurality of solder balls are connected to the plurality of connection parts on the board, thereby enhancing an assembling efficiency and decreasing a possibility of creating a defective connection of one of the plurality of solder balls.
However, the semiconductor chip which comprises the BGA package generates heat while operating. The heat causes the BGA package to expand. The BGA package and the plurality of solder balls adhered to the board then crack, and thus a defective connection may be created between one or more of the solder balls and the BGA package, or between the one or more solder balls and the board.
However, the conventional structure for mounting the BGA package to the board does not include a test unit to inspect the plurality of solder balls to detect the defective connection between the one or more solder balls and the BGA package, or between the one or more solder balls and the board.